test: add mustcall in test-dgram-connect-send-callback-buffer-length

add mustcall() on client.bind callback

Author: jyjunyz

test/parallel/test-dgram-connect-send-callback-buffer-length.js

@@ -17,8 +17,8 @@ const messageSent = common.mustCall(function messageSent(err, bytes) {
   client.close();
 });
 
-client.bind(0, () => {
+client.bind(0, common.mustCall(() => {
   client.connect(client.address().port, common.mustCall(() => {
     client.send(buf, offset, len, messageSent);
   }));
-});
+}));